Clonal expansion of the Belgian Phytophthora ramorum populations based on new microsatellite markers
Vercauteren, A. ; Dobbelaere, I. de; Grünwald, N. ; Bonants, P.J.M. ; Bockstaele, E. van; Maes, M. ; Heungens, K. - \ 2010
Molecular Ecology 19 (2010)1. - ISSN 0962-1083 - p. 92 - 107.
sudden oak death - fungicide resistance - genotypic diversity - 1st report - metalaxyl resistance - practical experience - ornamental plants - mating-type - infestans - pathogen
Co-existence of both mating types A1 and A2 within the EU1 lineage of Phytophthora ramorum has only been observed in Belgium, which begs the question whether sexual reproduction is occurring. A collection of 411 Belgian P. ramorum isolates was established during a 7-year survey. Our main objectives were genetic characterization of this population to test for sexual reproduction, determination of population structure, evolution and spread, and evaluation of the effectiveness and impact of control measures. Novel, polymorphic simple sequence repeat (SSR) markers were developed after screening 149 candidate loci. Eighty isolates of P. ramorum, broadly representing the Belgian population, were analyzed using four previously described and three newly identified polymorphic microsatellite loci as well as amplified fragment length polymorphisms. SSR analysis was most informative and was used to screen the entire Belgian population. Thirty multilocus genotypes were identified, but 68% of the isolates belonged to the main genotype EU1MG1. Although accumulated mutation events were detected, the overall level of genetic diversity within the Belgian isolates of P. ramorum appears to be limited, indicating a relatively recent clonal expansion. Based on our SSR analysis there is no evidence of sexual recombination in the Belgian population of P. ramorum. Metalaxyl use decreased the genetic diversity of P. ramorum until 2005, when the majority of the isolates had become resistant. Most genotypes were site-specific and despite systematic removal of symptomatic and neighbouring plants, some genotypes were detected over a period of several years at a single site, sometimes discontinuously, indicating (latent) survival of the pathogen at those sites
RNA-mediated gene silencing of superoxide dismutase (bcsod1) in Botrytis cinerea
Patel, R.M. ; Kan, J.A.L. van; Bailey, A.M. ; Foster, G.D. - \ 2008
Phytopathology 98 (2008)12. - ISSN 0031-949X - p. 1334 - 1339.
fungicide resistance - functional-analysis - neurospora-crassa - expression - plants - transformation - cutinase - disease - fungus - tool
Gene silencing is a powerful tool utilized for identification of gene function and analysis in plants, animals, and fungi. Here, we report the silencing of superoxide dismutase (bcsod1) in Botrytis cinerea through sense and antisense-mediated silencing mechanisms. Because superoxide dismutase (SOD) is a virulence factor, transformants were tested for phenotypic silencing in vitro and reduction in pathogenicity in planta. Plate-based assays with and without paraquat were performed to screen initial silencing efficiency, and a subset of transformants was used for in planta studies of virulence. Transformants exhibiting strongly decreased transcripts levels were recovered with both constructs but none of those exhibited a reduction in virulence in planta. Our investigations may help optimize a high-throughput gene silencing system useful for identifying potential gene targets for future fungal control.